Computer Science & Engineering

All Q&A

What is the need for normalization? Explain 2nd and 3rd normal form with example.

Consider the following relation:

EMP_PROJ { SSn, Pnumber, Hours, Ename, Pname, Plocation}

Assume { SSn, Pnumber} as primary key.

The dependencies are {SSn, Pnumber}→ Hours; SSn →Ename; Pnumber → {Pname, Plocation}.

Normalize the above relation into 2NF.

23 January, 2022

Develop a good description of the data, its relationships and constraints Produce a stable set of relations that Is a faithful model of the enterprise Is highly flexible

Consider the following relations and write down expressions for the following queries:

EMP (eid, ename, age, address, salary)

Works (eid, did, hours)

Dept (did, dname, managerid)

List the names of employees who work for the ‘Research’ department for 8 hours using Relational Algebra.
List the name and address of all employees with department number 5 using Relational Calculas.
Find the managerid of managers who manage only departments with budgets greater than 1 lac using SQL.
Find the employee who has highest salary using SQL.

23 January, 2022

Explain how to reduce a relationship set of an E-R diagram into relational schema.

23 January, 2022

There are several processes and algorithms available to convert ER Diagrams into Relational Schema. Some of them are automated and some of them are manual. We may focus here on the mapping diagram contents to relational basics.

State the steps involved in query processing. Why is the query optimization needed?

23 January, 2022

Query processing refers to the range of activities involved in extracting data from a database. The activities include translation of queries in high-level database languages into expressions that can be used at the physical level of the file system,